Vitamins: Separating Fact From Fiction

There are enough myths around vitamins to make an ancient Greek blush, and it's easy to see why.

We all know that vitamins and minerals are essential to good health -- it says so right there on the cereal box. And we live in the more-is-better era of Hummers, Big Gulps, and McMansions. Which raises the obvious question: if taking 100% of the Recommended Dietary Allowance (RDA) of, say, vitamin C is good enough to keep us going through the day, then why shouldn't taking 1,000% be enough to melt our fat, cure our blues, and let us leap tall buildings in a single bound?

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Meanwhile, the $19 billion-a-year dietary supplement industry continually reminds us that we can get our vitamins from a pill. Which invites yet another question: Why should we bother choking down bushels of brussels sprouts when we could get the same effect by sprinkling supplement shavings over our Boston cream pie?

If life were only that easy. The broad consensus from nutrition experts -- or at least the ones who aren't buying Hummers with the proceeds from supplement sales -- is that while vitamins are indeed essential, big doses are usually pointless and can even be harmful. And no pill is likely to ever adequately substitute for a healthy diet.

Why They Matter

Vitamins and minerals are substances your body needs for normal growth and functioning. Some facilitate crucial chemical reactions, while others act as building blocks for the body.

Nutritionists call vitamins and minerals "micronutrients" to distinguish them from the macronutrients such as proteins, carbohydrates, and fats that make up the bulk of our food. While micronutrients are vital for the proper processing of macronutrients, they're needed in smaller quantities. Think of it this way: If macronutrients are the gas in your engine, then micronutrients are like the motor oil, coolant, and battery fluid.

Micronutrient deficiency can lead to acute diseases with exotic names like scurvy, pellagra, and beriberi. Deficiency diseases were common in the U.S. until the 1940s, when the FDA-mandated fortification of common foods like bread and milk. These diseases are still common in many poorer countries.